1. Field of the Invention
The present invention relates to a memory management method and more particularly, to a memory management method using a flag indicating a state for each block, thus enabling high-speed processing.
2. Description of the Prior Art
Conventionally, for an electronic apparatus such as a computer as a main storage apparatus, a storage apparatus has been used to suffice the capacity of the main storage apparatus. As this storage apparatus, there can be exemplified a magnetic tape, magnetic disc, a magneto-optical disc, paper tape, memory card, and the like. Among them, the memory card has been widely used for its transfer rate of a comparatively high speed.
Moreover, the memory card is built in a still image pickup apparatus (so called still camera) and in a camera of a video tape recorder, so as to serve as a storage apparatus for storing a pickup information.
The memory card is constructed by storage means such as a semiconductor integrated circuit which is embedded in a frame, for example, made from a synthetic resin. The semiconductor integrated circuit is, for example a flash memory (electrically erasable programmable ROM (read only memory)).
It should be noted that in the aforementioned storage apparatus such as a memory card, management of a data stored there is carried out, for example, by way of distributed management method.
In the aforementioned distributed management method, a data stored in storage means (hereinafter, referred to as memory) of a storage apparatus is divided into a data erase unit such as a block, so as to create management information such as a block flag, logical address, and linkage information on block basis. Hereinafter, such a management information will be referred to as a distributed management information. In this distributed management method, when activating an electronic apparatus so as to read out and/or write into a data from/to the aforementioned storage apparatus, the electronic apparatus collects distributed management information on respective block in storage area of memory and reads out the information in storage means of the electronic apparatus, so as to create a central management table which enables to carry out an overall management of data of the blocks for carrying out the data management.
In a case when a flash memory is used as the memory of the memory card, normally, at a moment when a data of a predetermined block has become unnecessary, initialization on block basis is carried out, so as to erase the data written in the block all at once and this block enters a data writable state
Consequently, for example, when a data in a predetermined block has become unnecessary and a data write is carried out into another block or a processing other than data write is carried out, the aforementioned processing is carried out after initialization of the predetermined block.
Such an initialization on block basis takes about 5 to 60 (msec) per block. If respective processing is carried out after this initialization is complete, a plenty of time is required for the entire processing, preventing increase of the processing speed.